/* timeserv.c - a socket-based time of day server */#include  <stdio.h>#include  <unistd.h>#include  <sys/types.h>#include  <sys/socket.h>#include  <netinet/in.h>#include  <netdb.h>#include  <time.h>#include  <strings.h>#define   PORTNUM  13000   /* our time service phone number */#define   HOSTLEN  256#define   oops(msg)      { perror(msg) ; exit(1) ; }int main(int ac, char *av[]){	struct  sockaddr_in   saddr;   /* build our address here */	struct	hostent		*hp;   /* this is part of our    */	char	hostname[HOSTLEN];     /* address 	         */	int	sock_id,sock_fd;       /* line id, file desc     */	FILE	*sock_fp;              /* use socket as stream   */	char    *ctime();              /* convert secs to string */	time_t  thetime;               /* the time we report     */      /*       * Step 1: ask kernel for a socket       */	sock_id = socket( PF_INET, SOCK_STREAM, 0 );    /* get a socket */	if ( sock_id == -1 ) 		oops( "socket" );      /*       * Step 2: bind address to socket.  Address is host,port       */	bzero( (void *)&saddr, sizeof(saddr) ); /* clear out struct     */	gethostname( hostname, HOSTLEN );       /* where am I ?         */	hp = gethostbyname( hostname );         /* get info about host  */	                                        /* fill in host part    */	bcopy( (void *)hp->h_addr, (void *)&saddr.sin_addr, hp->h_length);	saddr.sin_port = htons(PORTNUM);        /* fill in socket port  */	saddr.sin_family = AF_INET ;            /* fill in addr family  */	if ( bind(sock_id, (struct sockaddr *)&saddr, sizeof(saddr)) != 0 )	       oops( "bind" );      /*       * Step 3: allow incoming calls with Qsize=1 on socket       */	if ( listen(sock_id, 1) != 0 ) 		oops( "listen" );      /*       * main loop: accept(), write(), close()       */	while ( 1 ){	       sock_fd = accept(sock_id, NULL, NULL); /* wait for call */		printf("Wow! got a call!\n");	       if ( sock_fd == -1 )		       oops( "accept" );       /* error getting calls  */	       sock_fp = fdopen(sock_fd,"w");  /* we'll write to the   */	       if ( sock_fp == NULL )          /* socket as a stream   */		       oops( "fdopen" );       /* unless we can't      */	       thetime = time(NULL);           /* get time             */					       /* and convert to strng */	       fprintf( sock_fp, "The time here is .." );	       fprintf( sock_fp, "%s", ctime(&thetime) ); 	       fclose( sock_fp );              /* release connection   */	}}